Mehta Casting for the Treatment of Early Onset Scoliosis: A Physician’s Perspective
Scoliosis in the infant and child presents unique challenges for the medical practitioner. Dr. James in 1951 was the first to describe the natural history of the progression of scoliosis in the young child.1 He noted in his series that the combination of early onset and rapid rate of progression leads to severe deformity at the end of growth. Early Onset Scoliosis (EOS) is defined as scoliosis > 10 degrees before the age of 10 years.2 Young children with EOS are at risk for impaired pulmonary function because of high risk of progression of the spinal deformity and thoracic constraints during a critical time of lung development. The treatment for EOS is very challenging because of the wide variability and heterogeneity of these patients. Additionally, many of these patients have other underlying complex medical diagnoses and disorders that need to be considered during their treatment.3 The current goal of treatment of EOS is to maximize the growth of the spinal column and thoracic cage by controlling the spinal deformity. Though surgical interventions can be employed, fusion surgery at a young age has been shown to lead to as high as a 50% decrease in thoracic growth compared to those children that do not have surgery.4 Casting, on the other hand, has been used as a less invasive method for the management and treatment of curve progression with increasing popularity in recent times.
Casting using plaster of Paris for the treatment of spinal deformity has a long history dating back to the 1800s. Dr. Lewis Sayre reported his technique and experience in a series of case reports in 1877 in the book “Spinal Disease and Spinal Curvature: Their Treatment by Suspension and the Use of the Plaster of Paris Bandage.”5 In one of the first medical texts to employee photography for demonstration of technique, he described using gravity traction attaching the patients’ arms to a pulley “tripod suspension derrick” letting them hang for several hours. After this he would apply a “Sayre jacket” a plaster of Paris body cast with no manipulation to hold the correction produced by the traction. In 1955, Dr. Risser described his technique for application of corrective cast using a specialized table.6 The patient lay supine on this special table frame supported by a longitudinal hammock strap with horizontal supports under the pelvis/thighs and shoulders. Longitudinal traction was applied via pelvic straps and a halter-type occiptio-mental strap. The nuance to his “Risser cast” technique, was that a window was cut in the posterior aspect and spinal fusion was performed in addition to the casting with variable success. Additionally, this was performed on more mature patients large enough to have reserve to recover from the process. In 1979, Drs. Mehta and Cotrel described the first formal casting technique for treatment of EOS at the “Sixth Symposium on Scoliosis” in London in 1979.7 Their report consisted of 21 children successfully treated with their technique of body cast application with early promising results maintaining curves until skeletal maturity however their technique was not described. 25 years later in 2005, Dr. Mehta published the seminal research article “Growth As a Corrective Force in the Early Treatment of Progressive Infantile Scoliosis.” She described series 136 patients treated with her casting technique. 94 children who started treatment at an average age of one year and seven months and a Cobb curve angle average of 32 degrees were successfully cured of their scoliosis by an average of age of 3 years and six months. In 42 patients who started treatment at a mean age of two years and six months with a mean Cobb angle of 52 degrees, treatment was shown to reduce but not cure the deformity.8 Following this impressive report, serial casting was quick to become an accepted method for the management of EOS as both a definitive treatment and to delay surgical procedures in the more severe cases.9
At our institution, we have taken to using the Mehta casting technique for the treatment of EOS as a standard of care. The desirable age of initiation is after 1 years of age as an older child is much safer from anesthetic complication. However, delaying too long has consequences, as it has been noted from our experience that the later the starting age the greater the risk for stiffer and less compliant curve. In patients with initial Cobb curve angle in the 20 to 30 degree range, the intent with serial casting is to cure the curve. In Dr. Mehta’s original series patients were cured even with curves up to 60 degrees, but in all those patients, casting was initiated within the first two year of life. We still consider casting for children with larger curves and older age at presentation however we make sure to explain to families that cure is less likely. The goal of treatment is curve control allowing the patient to mature buying time to safely perform a more definitive surgery at a later point after the lungs have had appropriate time to mature. Once a patient has been identified as a candidate for Mehta casting, they are assessed by our colleagues in the Anesthesia department to determine if they are safe to undergo general anesthetic. For maximal effect of the Mehta casting technique the patient has be completely sedate for the procedure. Attempts have been made at other institutions to cast an “awake” child, however this can lead to a traumatic experience for the child, and has been shown not to be as effective in curve control. An MRI is usually obtained at the time of the initial cast to assess if there are any underlying spinal cord abnormalities that could be driving the curve which sometimes need Neurosurgical intervention. If all clear, on average it has been noted that our patients typically will need roughly around 5 – 6 casts spaced 2 – 3 months apart
to achieve maximal results. The patient is brought in to the operating room and put to sleep under general anesthesia. The patient is then placed in a sliver impregnated shirt (to prevent skin irritation and odor) and a stockinette is placed around the thorax and abdominal circumferentially. The patient is then lifted and placed on a special Mehta casting table with a head rest and halter traction for the head and a cross bar post under the distal sacrum gluteal region. This set up allows for 360 degree freedom to access all aspects of the patient. Traction is setup extending from around the iliac crests to the foot of the bed. The legs are slightly flexed and placed on a rest to reduce lumbar lordosis. There is no objective way to know how much traction is necessary, it is solely based on subjective feel of the tension on the ropes and the look of the patient. The bony prominences are padded with felt, cotton padding is rolled from above the nipple line circumferentially down to the level of the greater trochanters of the hip. Plaster is applied with consistent tension around the thorax and abdomen. Cooperation with the anesthesiologist is necessary as during this part of the procedure, the lung pressures can increase and if necessary the cast will need to be cut off for the child’s safety. Some practitioners will place plaster shoulder straps (as described in Dr. Mehta’s original technique) however I find with a good iliac mold this added step is unnecessary. A mold is then applied to the convex side of the deformity, with a de-rotation maneuver. The felt pads are then folded up over the edges and a single layer of fiberglass cast is rolled over the plaster. A cast saw is used to cut areas to allow for appropriate hip flexion and space under the arm pits. An abdominal hole is cut to allow space for the abdomen to expand, and a hole is cut postero-laterallly over the area opposite the convex rib hump (usually the concave side) to accommodate the rib expansion being generated from pressure on the opposite side ribs. There is not a true consensus as to what clinical or radiographic determinants can be used to determine when to stop casting. It is the author’s preferred technique to stop casting when three consecutive in cast Cobb angles are less than 10 degrees or no change noted on consecutive casts. Other causes of termination include family desire to stop, or if the patient starts to have significant and progressive rib/ thoracic deformity related to pressure from the cast against the convex sided rib hump. It is typical after casting series to have some degree of mild rib deformity, however this improves in time. In the patients with larger curves, with goal of curve control, we work very closely with our orthotist for a continued ongoing treatment plan. At the time of the last cast, within a given series, a mold for a TLSO brace will be made, so when the cast is removed the patient can be transitioned to a TLSO for continued management. With the advent of temperature probes within the braces to monitor for compliance, we are able to objectively determine how well the brace is being utilized and help come up with ways with the family to improve adherence if compliance is an issue. In patients with milder curves at cast initiation that are “cured” with radiographic evidence of < 10 degrees of residual curve we do not routinely prescribe a TLSO.
Every patient presents with a different clinical scenario and different spinal deformity, so it is necessary to come up with a customized treatment program for each patient. The benefit of using a TLSO brace after Mehta casting in severe curves is still yet to be studied, but in the right patient can provide significant benefit potentially delaying surgery or in some cases avoiding it all together. Mehta casting is a powerful tool, and should be in the armamentarium of every medical provider tasked to provide care to this unique patient population.
Special Thanks: Dr. Brandon Ramo, Kara Davis CPO
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2. Tis JE, Karlin LI, Akbarnia BA, et al. Early onset scoliosis: modern treatment and results. J Pediatr Orthop. 2012;32(7):647-657. doi:10.1097/BPO.0b013e3182694f18.
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5. Sayre D. Spinal Disease and Spinal Curvature, Their Treatment by Suspension and the Use of the Plaster of Paris Bandage, by Lewis a. Sayre,...; 1877.
6. RISSER JC. The application of body casts for the correction of scoliosis. Instr Course Lect. 1955;12:255-259.
7. Mehta MH. The rib-vertebra angle in the early diagnosis between resolving and progressive infantile scoliosis. J Bone Joint Surg Br. 1972;54(2):230-243.
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